Air conditioning hose

Abstract

The present invention relates to a composite flexible hose, preferably for use in automotive air conditioning systems, with improved thermal resistance. The hose consists of an innermost core layer, a friction rubber layer, an intermediate reinforcement layer, and an external cover layer. The innermost layer is a non-plasticized polyamide mixed with a minor portion of polyolefin corresponding to the main rubber constituent of the friction coat layer. The friction coating is formed of a rubber composite of two EPDM rubbers at a weight ratio of 50/50 and 75 parts by weight of carbon black. The intermediate fibrous reinforcement layer is formed of aramid. The external layer is an acrylate rubber comprising a blend of two ethylene acrylates at a weight ratio of 50/50 and 80 parts by weight of carbon black.

What is claimed is:  
     
       1. A hose comprising an innermost layer, a friction coat layer, an intermediate reinforcing layer, and an outermost layer, characterized in that: 
       the innermost layer is comprised of non-plasticized polyamide;  
       the friction coat layer is comprised of a 50/50 weight percent blend of two ethylene propylene diene rubbers, the two rubbers having differing Mooney viscosities, and 75 parts by weight of carbon black  
       the intermediate reinforcing layer is comprised of aramid fibers; and  
       the outermost layer is comprised of a blend of two ethylene acrylic rubbers with differing Mooney viscosities.  
     
     
       2. The hose of  claim 1  wherein the non-plasticized polyamide is a blend of polyamide and polyolefin rubber with a weight ratio of polyamide and polyolefin rubber of 95/05 to 85/15. 
     
     
       3. The hose of  claim 2  wherein the polyolefin rubber is ethylene propylene diene. 
     
     
       4. The hose of  claim 1  wherein the ethylene acrylic rubber layer is comprised of a 50/50 weight percent blend of the two differing ethylene acrylic rubbers, and 80 parts by weight of carbon black. 
     
     
       5. A hose consisting of an innermost layer, a friction coating layer, an intermediate reinforcing layer, and an outermost layer, characterized by: 
       the innermost layer is comprised of non-plasticized nylon-6 blended with an ethylene propylene diene rubber at a weight ratio of 95/5 to 85/15;  
       the friction coat layer is comprised of a 50/50 weight percent blend of two ethylene propylene diene rubbers with differing Mooney viscosities, and 75 parts by weight of carbon black;  
       the intermediate reinforcing layer is comprised of adhesively treated aramid fibers; and  
       the outermost layer is comprised of a 50/50 weight percent blend of two ethylene acrylic rubbers having differing Mooney viscosities, and 80 parts by weight of carbon black.  
     
     
       6. The hose of  claim 5  where the weight ratio of nylon-6 to EPDM rubber is 94/6. 
     
     
       7. The hose of  claim 1  wherein the outermost layer is peroxide cured. 
     
     
       8. The hose of  claim 5  wherein the outermost layer is peroxide cured.